The 690C is a Turbo Commander. Garrett TPE-331 powered performer affectionately referred to by mechanics as a turbo-commode. Good airframe with simple mx. I worked on 690s on and off for number of years and later flew Westwinds.
The lineage from Aero Commander to Astra/G-100 is readily apparent. I suppose if the Jet Commander should be called a G-25 then a Westwind should be a G-50! (or maybe a G-1/2?) And why not? After all, at one time Grumman did own Gulfstream.
westhawk